Kirstin L. Whitmore
Department of Biology, Carleton College, Northfield, MN 55057 USA
Abstract. Pentaclethra macroloba is the most abundant tree species in the rainforest at the La Selva Biological Station, Costa Rica. However, not much is known about what affects its growth and allows it to grow competitively within the canopy of wet forests. The reproductive success of P. macroloba was studied in residual, alluvial, and swamp soils. The number of pods, number of seeds per pod, number of seeds per plot, number of seedlings per plot, and the average number of leaves per seedling per plot were recorded in 20 four-m2 plots in each soil type. The total number of pods, seeds, and seedlings was consistently higher in the alluvial and swamp soils than in the residual plots. The average number of seeds per pod and the average number of leaves per seedling per plot did not differ between soils. The total number of plots with and without seeds and seedlings was significantly different between soil type, but the number of plots with and without pods was not. Therefore, the reproductive success of P. macroloba until the seedling stage may be greater within alluvial and swamp soils.